We relate the autopsy findings of a case of pulmonary veno-occlusive disease which occurred in an HIV-infected intravenous drug abuser. This exceedingly rare disease, of unknown cause, is responsible for 10% of primary pulmonary hypertension. Histologically, the disease is characterized by a fibrous intimal thickening of small and medium sized pulmonary veins associated with congestive and dilated capillary network and alveolar haemorrhage. The occurrence of primary pulmonary hypertension in HIV positive patients is 25 times more frequent than in the general population. This is the third reported case of pulmonary veno-occlusive disease occurring in a HIV positive patient. It suggests the role of HIV in the pathogenesis of these vascular lesions.